This Is an Entirely Different Dog
Dogs with long hair must have haircuts somewhat more frequently than certain other breeds. The border collie has to visit the groomers somewhat more often than some other dogs. This person brought their collie into the groomer to get the undercoat combed out and for a cut. Not knowing the eventual consequence, they believed their dog had been stolen when they came to pick it up.
The dog in the after photo really doesn’t even appear like the same dog at all. He seems obviously lot smaller, but in the second shot he also looks like a puppy.